The present invention relates to a millimeter wave-radar mounted on automobiles and a method of manufacturing the same.
A millimeter wave-radar for automatic guidance and collision avoidance of a vehicle radiates an electromagnetic wave of a millimeter band in a desired direction and receives a reflected wave from objects in front of the radar to detect possible obstacles.
Conventional millimeter wave-radars have a problem that sidelobes of radiated electromagnetic waves are reflected by objects surrounding a radar fixing portion, resulting in unwanted objects also being detected in addition to targeted objects. A conventional countermeasure to deal with this problem involves installing a metal plate or electromagnetic wave absorber on a plane of and around the transmission/reception antenna in an antenna unit so that it protrudes from the antenna surface, in order to reduce sidelobes, as shown in, for example, JP-A-10-126146.
In the conventional technique described above, however, since the metal plate or radio wave absorber mounted around the transmission/reception antennas are separated from a radome enclosing the antennas, the construction and manufacturing process of the radar itself are complex and the metal plate or radio wave absorber is required to have a sufficient strength. This increases the thickness and weight of the absorber itself.
Another problem is that the metal plate or radio wave absorber is often installed, along with a car-mounted radar, on such locations as will be exposed to wind and rain and thus are required to have an improved weatherability.
An object of this invention is to provide a millimeter-wave radar which is light in weight with an excellent weatherability, prevents unwanted reflection of sidelobes and has an excellent detection performance.